Sometimes the tracker will give a 'false postivie'. So, before assuming you really are firewalled, stop all your TTD torrents and then start them again slowly and see if you still get the message. Also, you can check at a site like canyouseeme.org and see if the port you are using is really firewalled.

Well, do you have your mac firewall up? Did you forward your ports through it? How about your Airport Extreme? Did you forward your ports through it? (check out portforward.com and look under the portforwarding link). If you havne't tried to forward your ports since you added it, then that is why you are now firewalled.